It said: “Darling Granny. Thank you very much for the lovely doll’s house. I do love it, and I have unpacked the dining room and the hall. Love from Lilibet xxx.”
George VI, the Queen’s father, was quoted as saying: “Lilibet is my pride. Margaret is my joy.”
Philip also used the nickname, and wrote to his mother-in-law after being married to the Queen using it.
He said: “Lilibet is the only ‘thing’ in the world which is absolutely real to me and my ambition is to weld the two of us into a new combined existence that will not only be able to withstand the shocks directed at us but will have a positive existence for the good.”
Arthur Edwards, royal photographer wrote in The Sun how Philip was the last royal to call the monarch by her childhood nickname.
He said: “Later, seeing those haunting TV pictures of the Queen in black sitting all on her own in Chapel Quire, it dawned on me there is no longer anyone left in the world to call her “Lilibet”.
“Her mother did, her sister Margaret did and Philip did. They have all gone.
“It’s a lonely life being head of state in any country and you need a good partner to help you get through it each day.”
In a touching tribute to her husband, Her Majesty left a final letter and a wreath on top of Philip’s coffin on Saturday.
Some reports have indicated the Queen signed it as ‘Lilibet’, with the note appearing to say ‘In Loving Memory” on the front.
Buckingham Palace declined to share its contents, saying the note was “private”.
Patricia Mountbatten, Philip’s first cousin, told the Telegraph’s Gyles Brandreth: “He had no doubts at all about Lilibet as a person – as a future wife.
“He adored her. He loved her deeply – you could tell.”